Blood

Features to Know: The liquid matrix is called plasma. The numerous round, red cells are erythrocytes
(red blood cells). Erythrocytes lack nuclei, causing the cell to be biconcave (depressed
on both sides), resulting in a center with a lighter color. There are also a small
number of larger cells called leukocytes (white blood cells; 1), which have large
or multi-lobed nuclei.